2x^2+2x=4

I got to two separate answers, 2 & √5 -1

Which one is truly the answer?

Question

2x^2+2x=4

I got to two separate answers, 2 & √5 -1

Which one is truly the answer?

anonymous · Answer

plug them back into the original equation: 2x^2+2x and see which one gives you back 4.

anonymous · Answer

Neither of these..

anonymous · Answer

2x^2+2x=4

divide both sides by 2

x^2+x=4

x^2+x-4 = 0

solve using the quadratic formula

anonymous · Answer

2x^2 + 2x = 4

2x^2 + 2x -4 = 0

2 ( x^2 + x - 2) = 0

2 (x-1) (x+2) = 0

x-1=0 : x=1
x+2=0 : x=-2

anonymous · Answer

I see what I did wrong! Thanks so much!

comm.dan · Answer

@Virgo91684 It is just basically Factoring by Grouping for polynomials

comm.dan · Answer

|dw:1362362891009:dw| @Virgo91684

anonymous · Answer

Oh the infinity symbol

comm.dan · Answer

Thank you for that reminder @Virgo91684

comm.dan · Answer

Always remember this for when finding domain from something, Domain is always all real numbers @Virgo91684

anonymous · Answer

So no negatives?

comm.dan · Answer

Nope not ever, that is what I remember my teacher said to me. @Virgo91684

comm.dan · Answer

The first answer for the range that you sent me might be wrong, I just need the original problem please. @Virgo91684

anonymous · Answer

f(x) = -sqrt(x-3)

comm.dan · Answer

What does the -sqrt stand for? @Virgo91684

anonymous · Answer

√